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Mark O'Neal

8mm rope belay

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I'm planning on using an 8mm rope for the first time on a moderate snow climb. So I've been experimenting with how belaying would feel on the smaller rope. I realize the forces are much lower on the slope, but I experimented using full body weight.

 

Long story short, I found that I couldn't create enough friction with a munter or an ATC on a single 8mm strand through 2 carabiners to be able to support my full body weight. After playing around a little I put the rope through the ATC normally, but then passed the free end back through the other side of the ATC (making an X across the top of the ATC), through the carabiner again and back up through the ATC. I created a ton of friction and was able to fully support and easily lower my full body weight.

 

My question is: Is there anything wrong with setting up my ATC in this manner? It seemed OK to me when I looked at it, but I've never seen anyone do anything like that before.

 

Thanks for any advice.

 

 

Mark

 

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If I understand it right, it seems like it would put alot of twists in the rope. While not a safety issue, it is a convience and time issue. Maybe you could post of photo of it in action.

 

There is a video post somewhere on this site of a monster munter which should work for you on the 8mm rope. (if you end up rapping on vertical terrain on a single strand)

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I saw the monster munter video after I made the post. I haven't tested it with body weigh yet, but I quickly set it up in the house. It had amazing friction and was easy to tie. It had more friction in fact than my modified ATC setup. I pulled a rope length through the ATC and didn't notice a ton of twisting, but there was a little.

 

Here's a picture of my ATC setup and for reference the monster munter.

 

DSCN1926.JPGDSCN1927.JPG

Edited by Mark O'Neal

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Get a smaller belay device!! That will help a lot!! I have rapped 8 mill with a reversino and had no issues, good friction.

 

I have rapped several times using 5 mil static line with the reversino full weight and it was ok, really had to hold onto rope and use glove. But no special figuring was needed.

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Hmm. That's a thought. It appears like Petzl recently quit making the Reversino though. It seems to have limited availability. They offer the Verso now instead. Anyone used that on a thin rope yet?

 

Still looking for some more comments on my strange ATC configuration.

 

 

Mark

 

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I'd avoid the monster munter, since you're talking about supporting your weight. Using the munter will introduce a lot of twists to your rope. Instead, try taking the breaking strand and looping it once or twice through a krab off your leg loop- the turns should give you the friction needed. Also, you kight consider just using a 7mm perlon prussik backup, which would lend extra friction and security.

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If twisting your rope is the issue with the monster munter then I think you should try it. It is no worse ten the devicesyou are suggesting.

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According to the video, there should be less twists with the monster munter vs a regular munter. Something about the second wrap undoing the munter twists.

 

If you use a perlon prussik backup, use something smaller than a 7mm or it will not grab. You need at least a couple mm difference for the prussik to work. Use a 6mm or 5mm cord for a prussik.

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Yea, putting on a prussik or an autoblock is a good idea too. When I was playing around in the yard, I practiced prussiking up the 8mm rope using 5mm cord and it grabs plenty good.

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I used to just use an extra beaner on the harness on the belay hand side of the ATC, run the rope through that for an extra change of direction and more friction.

 

Ever since an icy rope slipped through my gloved hand I've been using a prussick on the belay hand side of the rope. It gives enough extra friction all by itself and you can stop and do things with both hands, no need to hold the rope.

 

What if a rock comes down and knocks you unconscious? Your going to slide to/off the end of the rope.

 

For an 8 mil or smaller you need a 4mm prussick cord.

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According to the video, there should be less twists with the monster munter vs a regular munter. Something about the second wrap undoing the munter twists.

 

Without trying it, I believe that. I learned long ago that the Munter does not twist the rope if you use it in a configuration where the load end and the guard end of the rope head the same direction from your locking carabiner (note: "'biner" not "beaner").

 

For use as a top-rope belay device or for lowering someone, for example, the Munter does not twist the rope and it is very simple to operate compared to mechanical devices. I use the munter when climbing sometimes and, in more than one situation where I was setting up the belay station for someone else (inexperienced) to operate, I have opted for it because I actually thought it more secure than setting them up with a figure eight or ATC or whatever.

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the basis for belaying force is the number of bends in the rope. A normal ATC setup has about 2 full 180 degree bends. (180 at the biner and two 90 degrees roughly at the entry and exit points of device) Your setup has three full 180 bends and the two 90 degree bends for a total of 720 degrees. This is twice as much as a normal setup so it would have roughly twice the friction power.

 

But the way it corkscrews around the device is going to create one mother of a twisting cluster f^&k. (I think as I haven't tried your system)

 

That monster munter has something like 1330 degrees of bend (maybe more) plus rope rubbing on rope four times for added friction. I think a regular munter has 720 degrees roughly plus rope rubbing on rope one time. I think the rope will break before the MM slips.

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I have the same rope, and use it with a Reverso 3; works well in high friction mode. If you're trying to use that rope as a single lead line, you're probably taking a big chance. Use it as a twin rope with a Reverso or BD XP or guide, you'll be fine. The BD ATC you show does not have a high friction mode.

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The rope you are using is not a static line right? In the photo, it looks alot like a static perlon from the spool.

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i just got an 8mm rope and tried using a 6mm prusik and it doesn't work that well just messing around at home--do i need to go to a 5mm?

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prussik friction is a function on difference in diameter and the physical characteristics of the two sheaths. Your cords and rope maybe too new and "slippery" to work with 3 wraps but will when it gets fuzzier. Until then, you could either add more wraps (try 4 or 5 or go crazy) or use a 5mm cord. Kliemhist hitches are easy to add crazy amounts of wraps.

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The rope you are using is not a static line right? In the photo, it looks alot like a static perlon from the spool.
I think the rope looks like an "Edelweiss Discover 8mm x 30m Super Dry Twin Rope"

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The rope you are using is not a static line right? In the photo, it looks alot like a static perlon from the spool.
I think the rope looks like an "Edelweiss Discover 8mm x 30m Super Dry Twin Rope"

 

Correct! Edelweiss Discover 8mm x 30m Super Dry Twin Rope. We're using it as a single for glacier travel and to climb moderate snow slopes (Gannett Peak in WY).

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But the way it corkscrews around the device is going to create one mother of a twisting cluster f^&k. (I think as I haven't tried your system)

 

I pulled a rope length through my setup and it imparted less twist than a munter. I don't know that I'll necessarily use it. Just thinking of options that aren't safety hazards. I'm thinking the MM would have too much friction on a snow slope to be usable to lower someone. I've been thinking of picking up the BD XP which might give me the extra friction I'm looking for but not be a specialized piece like a Reverso.

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The rope you are using is not a static line right? In the photo, it looks alot like a static perlon from the spool.
I think the rope looks like an "Edelweiss Discover 8mm x 30m Super Dry Twin Rope"

 

Correct! Edelweiss Discover 8mm x 30m Super Dry Twin Rope. We're using it as a single for glacier travel and to climb moderate snow slopes (Gannett Peak in WY).

 

this is the exact rope i just bought.

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did you try the test while loaded? Loaded would make more twists.

 

The munter should be attached to an anchor usually above you. Otherwise it is too hard to pull rope through. (try belaying a munter from the belay loop) Usually belaying on snow is done from a seated snow anchor position in which a munter would suck ass. Belaying off a device on the belay loop or better yet a hip belay is normal for belaying on snow. (unless you are talking about crevasse rescue)

 

glad to hear that it is a dynamic line. :)

 

 

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IMO the Reverso is not a specialized piece of equipment. The only real difference between the Reverso & the XP, is the Reverso can be used as an autoblock; very similar to the BD ATC Guide.

 

I just completed an alpine climb with a rock section using two of the Edelwiess 8mm ropes as twin ropes with a reverso. Worked excellently for both belay and repel on high friction mode.

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I use a reverso in high friction mode with 2 biners on 8mm ropes, and haven't had any problems.

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